Muller U.S. Pat. No. 3,083,647 discloses a fluid metering and pumping device in which a multiplicity of pressure bars driven by a camshaft with offset eccentrics progressively collapse a tube to produce a peristaltic advancement of fluid through that tube. While such a system might be effective for tubing having an inside diameter (ID) of 0.20 inches or more, the size and complexity of the apparatus would tend to be objectionable even for such an application. Such complexity--the numerous parts and their assembly--would become prohibitive if such a system were to be used with relatively small-size tubing (i.e., below 0.1 inches ID) and if the dimensions of the pump were to be kept to a minimum. Miniaturization could be achieved only with considerable effort and expense and at the risk of performance variations and uncertainties that would make such an apparatus unsuitable as a pump for metering medical or biological fluids.
Other patents such as Roudaut U.S. Pat. No. 3,229,643, Wall U.S. Pat. No. 3,981,633, and Chanton U.S. Pat. No. 3,233,553 disclose somewhat similar pumps in which the shafts and eccentrics are disposed internally rather than externally in relation to the flexible tubes. Such systems avoid some of the complexities and inherent problems associated with the pressure bar system disclosed by Muller; however, they present other problems that tend to exclude their use in medical systems or in any other systems where low-volume pumping at predetermined flow rates, in a precise and reliable manner, is deemed essential. It is also apparent that replacement of the tubing, as well as cleaning and sterilization of the fluid-contacting components so that the pumps might be used successively by the same or different patients, would be extremely difficult if not impossible.
Other patents illustrative of the state of the art are U.S. Pat. Nos. 3,067,692, 2,722,893, 1,874,667, 2,414,355, and 2,249,806.